Testing of a photovoltaic panel

ABSTRACT

A method for testing a photovoltaic panel connected to an electronic module. The electronic module includes an input attached to the photovoltaic panel and a power output. The method activates a bypass to the electronic module. The bypass provides a low impedance path between the input and the output of the electronic module. A current is injected into the electronic module thereby compensating for the presence of the electronic module during the testing. The current may be previously determined by measuring a circuit parameter of the electronic module. The circuit parameter may be impedance, inductance, resistance or capacitance.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/269,403, filed on Feb. 6, 2019, (now issued as U.S. Pat. No.11,183,969), which is a divisional of U.S. patent application Ser. No.13/015,219, filed on Jan. 27, 2011, (now issued as U.S. Pat. No.10,693,415), which is a continuation-in-part application of U.S. patentapplication Ser. No. 12/314,115 filed on Dec. 4, 2008, (now issued asU.S. Pat. No. 8,324,921), which is a Non-Provisional of U.S. ProvisionalApplication 61/039,050 filed Mar. 24, 2008 and U.S. Provisional60/992,589 filed Dec. 5, 2007, the disclosures of which are includedherein by reference.

TECHNICAL FIELD

The present invention relates to production testing of photovoltaicpanels, and more specifically to testing of photovoltaic panels whichinclude integrated circuitry.

DESCRIPTION OF RELATED ART

Current voltage (IV) characteristics of a conventional photovoltaicpanel are measured using a flash tester. The flash tester measureselectrical current characteristics of a photovoltaic panel during asingle flash of light of duration typically within one millisecondemitted by the flash lamp. The measurement procedure is based on knownproperties of a reference photovoltaic panel which has beenindependently calibrated in an external laboratory. The externallaboratory has determined accurately the short circuit currentcorresponding to standard test conditions (STC) using an AM1.5Gspectrum. AM1.5G approximates a standard spectrum of sunlight at theEarth's surface at sea level at high noon in a clear sky as 1000 W/m2.“AM” stands for “air mass” radiation. The ‘G’ stands for “global” andincludes both direct and diffuse radiation. The number “1.5” indicatesthat the length of the path of light through the atmosphere is 1.5 timesthat of the shorter path when the sun is directly overhead. During flashtesting homogeneity of irradiance over the photovoltaic panel isobtained by a 6-meter distance between the flash lamp and thephotovoltaic panel.

Reference is now made to FIG. 2 which illustrates a conventional flashtesting system 7. The flash testing system 7 includes a photovoltaicpanel 10, flash tester 17 and a flash lamp 16, placed inside a closedlightproof cabin 19 which is painted black inside. Alternatively, blackcurtains minimize the intensity of reflections towards photovoltaicpanel 10 from the interior surfaces of the cabin. The homogeneity ofirradiance over area of photovoltaic panel 10 is measured by placing anirradiance sensor in various positions of the measurement plane. Duringthe flash testing procedure, a flash tester 17 is connected to theoutput of photovoltaic panel 10. The measurement procedure starts with aflash test of a reference photovoltaic panel. The short circuit currentis measured during an irradiance corresponding to AM1.5G. The referencephotovoltaic panel is then exchanged for the test photovoltaic panel.During a subsequent flash, the irradiance sensor triggers acurrent-voltage (IV) measurement procedure at the same irradiance asduring the measurement of the reference photovoltaic panel.

Conventional photovoltaic panels are typically connected together inseries to form strings and the strings are optionally connected inparallel. The combined outputs of the connected photovoltaic panels aretypically input to an inverter which converts the generated directcurrent voltage to alternating current of the grid. Recently,photovoltaic panels have been designed or proposed with integratedcircuitry.

Reference is now made to FIG. 1 which illustrates schematically aphotovoltaic system 14 with a circuit or electronic module 12 integratedwith a photovoltaic panel 10. The term “electronic module” as usedherein refers to electronic circuitry integrated at the output of thephotovoltaic panel. The “electronic module” itself may be of the priorart or not of the prior art. A representative reference (Cascade DC-DCConverter Connection of Photovoltaic Modules, G. R. Walker and P. C.Sernia, Power Electronics Specialists Conference, 2002. (PESC02), Vol. 1IEEE, Cairns, Australia, pp. 24-29) proposes use of DC-DC convertersintegrated with the photovoltaic panels. The DC-DC converter integratedwith the photovoltaic panel is an example of an “electronic module”.Other examples of “electronic modules” include, but are not limited to,DC-AC inverters and other power conditioning electronics, as well assensing and monitoring electronics.

Another reference of the present inventors which describes an example ofphotovoltaic system 14 including photovoltaic panel 10 integrated withelectronic module 12 is US20080143188, entitled “Distributed PowerHarvesting Systems Using DC Power Sources”.

The “electronic module” herein may have electrical functionality, forinstance for improving the electrical conversion efficiency ofphotovoltaic system 14. Alternatively, “electronic module” as usedherein may have another functionality unrelated to electricalperformance. For instance in a co-pending patent application entitled,“Theft detection and Prevention in a Power Generation System”, thefunction of electronic module 12 is to protect photovoltaic system 12from theft.

Since a standard flash test cannot typically be performed on panel 10after integration with electronic module 12, for instance because thepresence of module 12 affects the results of the standard test, it wouldbe advantageous to have a system and method for flash testing ofphotovoltaic system

The term “photovoltaic panel” as used herein includes any of: one ormore solar cells, cells of multiple semiconductor junctions, solar cellsconnected in different ways (e.g. serial, parallel, serial/parallel), ofthin film and/or bulk material, and/or of different materials.

BRIEF SUMMARY

According to aspects of the present invention there is provided a methodfor testing a photovoltaic panel connected to an electronic module. Theelectronic module includes an input attached to the photovoltaic paneland a power output. The method activates a bypass to the electronicmodule. The bypass provides a low impedance path between the input andthe output of the electronic module. A current is injected into theelectronic module thereby compensating for the presence of theelectronic module during the testing. The current may be previouslydetermined by measuring a circuit parameter of the electronic module.The circuit parameter may be impedance, inductance, resistance orcapacitance. The electronic module is preferably permanently attached tothe photovoltaic panel. The activation of the bypass may be byexternally applying either an electromagnetic field or a magnetic field.The electronic module may be either a DC to DC converter, DC to ACconverter or maximum power point tracking converter. The electronicmodule performs maximum power point tracking to maximize power at eitheran input or an output of the electronic module. The bypass may include areed switch, a reed relay switch, a solid state switch or a fuse. Thebypass may include a fuse 30 which has a power supply connected directacross the fuse where a current flow from the power supply, de-activatesthe bypass by blowing the fuse. The bypass may typically include a solidstate switch. The bypass may further include a fuse and a parallelconnected switch which is disposed between and connected in parallelwith the photovoltaic panel and the electronic module. A power supplyunit is typically connected across the outputs of the electronic moduleand closing the switch, provides a low impedance path across the fuse,thereby blowing the fuse. The parallel-connected switch may be a siliconcontrolled rectifier, reed switch, solid state switch or reed relay.Blowing the fuse typically de-activates the bypass of the electronicmodule. De-activating the bypass is preferably performed bycommunicating with the electronic module.

According to aspects of the present invention there is provided a devicefor testing a photovoltaic panel system including a photovoltaic panelconnected to an electronic module. The electronic module includes atleast one input attached to the photovoltaic panel and at least onepower output. The device includes a bypass operatively attached to theelectronic module. The bypass provides a low impedance path between theat least one power output and the at least one input of the electronicmodule. A current injector may be operatively attached to the electronicmodule. A circuit parameter analyzer is operatively attached to theelectronic module. The circuit parameter analyzer is adapted to measurea circuit parameter of the electronic module. A processor may beoperatively attached to the circuit parameter analyzer. The processor ispreferably configured to program the programmable current injector basedon the circuit parameter. The current may be determined by measuring acircuit parameter of the electronic module. The circuit parameter may beimpedance, inductance, resistance or capacitance.

The bypass may further include a bypass component which has at least oneswitch and at least one fuse. The bypass component typically connectsthe at least one power output and the at least one input of theelectronic module. The at least one switch may be a magneticallyactivated reed switch, an electro-magnetically activated reed relayswitch or a solid state switch. The electronic module typically performsmaximum power point tracking. The electronic module may perform either:DC to DC conversion or DC to AC inversion.

According to yet another aspect of the present invention there isprovided a method for a device used whilst testing a photovoltaic panelsystem. The photovoltaic panel system includes a photovoltaic panelconnected to an electronic module. The electronic module includes atleast one input attached to the photovoltaic panel and at least onepower output. The device typically includes a current injectoroperatively attached to the least one power output and to a test module;a circuit parameter analyzer operatively attached to the electronicmodule and a processor operatively attached to the circuit parameteranalyzer. The method typically attaches a bypass to the electronicmodule. The bypass preferably provides a low impedance path between theat least one power output and the at least one input of the electronicmodule. Prior to testing the panel a circuit parameter of the least onepower output is measured, followed by the current injector beingprogrammed with a parameter based on the measuring. Injecting currentand triggering the test module is typically performed simultaneously,thereby compensating for the presence of the electronic module duringthe triggering.

The foregoing and/or other aspects will become apparent from thefollowing detailed description when considered in conjunction with theaccompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 illustrates an electrical power generation system including aphotovoltaic panel and electronic module.

FIG. 2 illustrates a flash test module of the prior art.

FIG. 3 illustrates a general equivalent circuit, representing theelectronic module shown in FIGS. 1 and 2 with a bypass applied,according to a feature of the present invention.

FIG. 4 shows a flow chart of a method to flash test a photovoltaic panelaccording to an embodiment of the present invention.

FIG. 5 is an activated bypass circuit, according to an embodiment of thepresent invention, of an electronic module connected to a photovoltaicpanel and test module.

FIG. 6 is a de-activated bypass circuit, according to an embodiment ofthe present invention of an electronic module connected to aphotovoltaic panel.

FIG. 7 is an activated bypass circuit, according to another embodimentof the present invention, of an electronic module connected to aphotovoltaic panel and test module.

FIG. 8 is a de-activated bypass circuit, according to another embodimentof the present invention of an electronic module connected to aphotovoltaic panel.

FIG. 8 a is a de-activated bypass circuit using a fuse and power supply,according to another embodiment of the present invention of anelectronic module connected to a photovoltaic panel.

FIG. 8 b is a de-activated bypass circuit using a fuse, power supply andsilicone controlled rectifier (SCR), according to yet another embodimentof the present invention of an electronic module connected to aphotovoltaic panel.

FIG. 9 is an activated bypass circuit, according to yet anotherembodiment of the present invention, of an electronic module connectedto a photovoltaic panel and test module.

FIG. 10 is a de-activated bypass circuit, according to yet anotherembodiment of the present invention of an electronic module connected toa photovoltaic panel.

FIG. 11 illustrates yet another way in which to de-activate bypass oncea flash test has been performed according to a feature of the presentinvention.

FIG. 12 a shows a module connected to a compensation unit according to afeature of the present invention.

FIG. 12 b shows further details of the compensation unit shown in FIG.12 a , according to a feature of the present invention.

FIG. 12 c shows a simulation circuit, according to a feature of thepresent invention.

FIG. 12 d shows simulation results of a test circuit shown in FIG. 12 c, according to a feature of the present invention.

FIG. 12 e shows another simulation circuit, according to a feature ofthe present invention.

FIG. 12 f shows the simulation results a test circuit shown in FIG. 12 e, according to a feature of the present invention.

FIG. 12 g shows a simulation circuit, according to a feature of thepresent invention.

FIG. 12 h shows the compensated simulation results of a test circuit,according to a feature of the present invention.

FIG. 12 i which shows a method, according to a feature of the presentinvention.

FIG. 12 j which shows a method, according to a feature of the presentinvention.

The foregoing and/or other aspects will become apparent from thefollowing detailed description when considered in conjunction with theaccompanying drawing figures.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings; wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

Reference is now made back to FIG. 1 which illustrates electrical powergeneration system 14, including photovoltaic panel 10 connected toelectronic module 12. In some embodiments of the present invention,electronic module 12 is “permanently attached” to photovoltaic panel 10.In other embodiments of the present invention, electronic module isintegrated with photovoltaic panel 10 but is not “permanently attached”to photovoltaic panel 10. The term “permanently attached” as used hereinrefers to a method or device for attachment such that physical removalor attempt thereof, e.g. of electronic module 12 from photovoltaic panel10, would result in damage, e.g. to electronic module 12 and/or panel10. Any mechanism known in the art for “permanently attaching” may beapplied indifferent embodiments of the present invention. Whenelectronic module 12 is permanently attached to the photovoltaic panel10, the operation of photovoltaic panel 10 ceases or connections thereofare broken on attempting to remove electronic module 12 fromphotovoltaic panel 10. One such mechanism for permanently attaching usesa thermoset adhesive, e.g. epoxy based resin, and hardener.

Referring to FIG. 3 , an example of electronic module 12 is illustratedin more detail. Electronic module 12 connects photovoltaic panel 10 andtest module 20. Impedance Z1 is the series equivalent impedance ofelectronic module 12. Impedance Z2 is the equivalent input impedance ofelectronic module 12. Impedance Z3 is the equivalent output impedance ofelectronic module 12. Bypass link 40 when applied between the output ofphotovoltaic panel 10 and the input of test module 20 eliminates theeffects of series equivalent impedance Z1 during a flash test. Withbypass link 40 applied, impedances Z2 and Z3 are connected in parallelwith resulting shunt impedance Z_(T) given in Eq. 1.

$\begin{matrix}{Z_{T} = \frac{Z\; 2 \times Z\; 3}{{Z\; 2} + {Z\; 3}}} & {{Eq}.\mspace{14mu} 1}\end{matrix}$

Where impedances Z2 and Z3 are both high in value, ZT will have aninsignificant effect upon a flash test of photovoltaic panel 10.

Reference is made to FIGS. 4, 5 and 6 which illustrate embodiments ofthe present invention. FIG. 4 illustrates a flowchart for a method forflash testing a photovoltaic panel 10 by bypassing an electronic module12 according to embodiments of the present invention. FIGS. 5 and 6 arecorresponding system drawings according to embodiments of the presentinvention of electrical power generation system 14. FIG. 5 illustratesbypass 40 when bypass 40 is activated. With reference to FIG. 5 , asingle pole single throw (SPST) switch 50 activated by magnetic field ofmagnet 52 connects the output of photovoltaic panel 10 and the input oftest module 20 to bypass electronic module 12 during a flash test ofphotovoltaic panel 10. SPST switch 50 in an embodiment of the presentinvention is a reed switch (for example, Part no: HYR 2031-1, AlephAmerica Corporation NV USA) or a reed relay, or a solid state switch.Bypass 40 of electronic module 12 is activated (step 201) by applying amagnetic field 52 to SPST switch 50 causing SPST switch 50 to close asshown in FIG. 5 . The flash test is performed (step 203) using flashtest module 20. After the flash test of photovoltaic panel 10, bypass 40of electronic module 12 is de-activated by the removal of magnetic field52 to SPST switch 50 (step 205). FIG. 6 illustrates photovoltaic panel10 connected to the input of electronic module 12, with SPST switch 50bypass de-activated (step 205).

Reference is made to FIGS. 7 and 8 which illustrate another embodimentof the present invention. FIG. 7 illustrates bypass 40. With referenceto FIG. 7 , a fuse 50 a connects the output of photovoltaic panel 10 andthe input of test module 20 to bypass electronic module 12 during aflash test of photovoltaic panel 10. Referring back to FIG. 4 , bypass40 of electronic module 12 is activated (step 201) by virtue of fuse 50a being in an un-blown state as shown in FIG. 7 and SPST switch 5 bbeing open circuit. SPST switch 5 b in an embodiment of the presentinvention is a reed switch (for example, Part no: HYR 2031-1, AlephAmerica Corporation NV USA) or a reed relay, or a solid state switch.The flash test is performed (step 203) using flash test module 20. Afterthe flash test of photovoltaic panel 10, bypass 40 of electronic module12 is de-activated (step 205). FIG. 8 shows bypass 40 being de-activated(step 205). FIG. 8 shows photovoltaic panel 10 connected to the input ofelectronic module 12 and a power supply unit (PSU) 13 applied across theoutput of electronic module 12. SPST switch 5 b is in a closed positionbecause of the application of magnetic field 52.

Reference now made to FIG. 11 which illustrates yet another way in whichto deactivate bypass 40 (step 205) once a flash test has been performed(step 203) according to a feature of the present invention. Photovoltaicpanel 10 is connected to the input of buck boost converter 12 a. Theoutput of buck boost converter 12 a is connected to PSU 13. Duringdeactivation of bypass 40 (step 205), a power line communicationsuperimposed on the output of buck boost converter 12 a via PSU 13, awireless signal applied in the vicinity of buck boost converter 12 a, orbased on some logic circuitry—i.e. a specific supply voltage applied byPSU 13 causes MOSFETS G_(C) and G_(A) to turn on. MOSFETS G_(C) andG_(A) turned on causes a short circuit current I_(SC) to flow from PSU13 and through fuse 50 a. The short circuit I_(SC) current blows fuse 50a making fuse 50 a open circuit and bypass 40 is de-activated (step205).

The closure of SPST switch 5 b and application of PSU 13 applied acrossthe output of electronic module 12, causes a short circuit currentI_(SC) to flow from PSU 13 through fuse 50 a and SPST switch 5 b. Theshort circuit I_(SC) current blows fuse 50 a making fuse 50 a opencircuit and the removal of magnetic field 52 de-activates bypass 40(step 205).

An alternative way of de-activating bypass 40 (step 205) is shown inFIG. 8 a . FIG. 8 a shows photovoltaic panel 10 connected to the inputof electronic module 12 and a power supply unit (PSU) 13 applied acrossfuse 50 a. The application of PSU 13 across fuse 50 a, causes a shortcircuit current I_(SC) to flow from PSU 13 and through fuse 50 a. Theshort circuit I_(SC) current blows fuse 50 a making fuse 50 a opencircuit and bypass 40 is de-activated (step 205).

Another way of de-activating bypass 40 (step 205) is shown in FIG. 8 b .FIG. 8 b shows photovoltaic panel 10 connected to the input ofelectronic module 12 and a power supply unit (PSU) 13 applied across theoutput of electronic module 12. The anode and cathode of a siliconcontrolled rectifier (SCR) 15 is connected in parallel across the outputof photovoltaic panel 10 and the input of electronic module 12. The gateof an SCR 15 is connected inside electronic module 12 in such a way thatthe application of PSU 13 across the output of electronic module 12causes a gate signal to be applied to the gate of SCR. A gate pulseapplied to SCR 15 switches SCR 15 on. Alternative ways to get a pulse tothe gate of SCR 15 include, power line communication superimposed on theoutput of electronic module 12 via PSU 13, a wireless signal applied inthe vicinity of electronic module 12, or based on some logiccircuitry—i.e. a specific supply voltage applied by PSU 13 causes a gatesignal to be applied to SCR 15. A gate signal applied to SCR 15 andapplication of PSU 13 applied across the output of electronic module 12,causes a short circuit current I_(SC) to flow from PSU 13 through fuse50 a and SCR 15. The short circuit I_(SC) current blows fuse 50 a makingfuse 50 a open circuit and bypass 40 is de-activated (step 205).

Reference is now made to FIGS. 4, 9 and 10 which illustrate anotherembodiment of the present invention of electrical power generationsystem 14, particularly applicable in cases when the resulting shuntimpedance Z_(T) is small enough to disrupt the results of the flashtest, such as being less than 1 Mega Ohm in electronic module 12.Referring back to FIG. 4 , FIG. 4 illustrates a flowchart for a methodfor flash testing a photovoltaic panel 10 by bypassing an electronicmodule 12 according to embodiments of the present invention. FIG. 4includes step 201 of activating a bypass, step 203 performing the flashand de-activating the bypass, step 205.

FIG. 9 illustrates bypass 40 when bypass 40 is activated. With referenceto FIG. 9 , a single pole double throw (SPDT) switch 70, SPST switch 72and SPDT switch 74, activated by magnetic field of magnet 52, connectsthe output of photovoltaic panel 10 and the input of test module 20 toperform the function of bypassing electronic module 12 during a flashtest of photovoltaic panel 10. SPDT switches 70 and 74 in an embodimentof the present invention is a reed switch (for example, Part no:HYR-1555-form-C, Aleph America Corporation Reno, Nev. USA) or a reedrelay, or a solid state switch. SPDT switches 70 and 74 when activatedby magnetic field 52 provide open circuit impedance in place of shuntimpedance Z_(T) when electronic module 12 is being bypassed during aflash test of photovoltaic panel 10. The bypass 40 of electronic module12 is activated (step 201) by applying a magnetic field 52 to SPSTswitch 72 and SPDT switches 70 and 74 causing switch positions shown inFIG. 9 . Next the flash test is performed (step 203) using flash testmodule 20. After the flash test of photovoltaic panel 10, the bypass ofelectronic module 12 is de-activated by the removal of magnetic field 52to SPST switch 50 and SPDT switches 70 and 74 (step 205). FIG. 10 showsphotovoltaic panel 10 connected to electronic module 12 with SPST switch50 and SPDT switches 70 and 74 de-activated (step 205).

During operation of electrical power generation system 14, DC power isproduced by photovoltaic panel 10 and transferred to the input ofelectronic module 12. Electronic module 12 is typically a buck-boostconverter circuit to perform DC to DC conversion or an inverterconverting DC to AC or a circuit performing maximum power point tracking(MPPT).

Reference is now made to FIG. 12 a which shows a module 12 a connectedto compensation unit 17 a according to a feature of the presentinvention. Photovoltaic panel 10 is connected to the input of buck boostconverter 12 a. The output of buck boost converter 12 a is connected tocompensation unit 17 a at terminals A and the other terminals B of unit17 a is connected to conventional flash tester 17. Fuse 50 a provides alow impedance serial path between panel 10 and conventional flash tester17/compensation unit 17 a. With bypass link 50 a applied (i.e. fuse link50 a is not blown), the shunt impedance (Z_(T)) of circuit 12 aconnected to conventional flash tester 17/compensation unit 17 a comesfrom capacitors C1 and C2 now connected in parallel in circuit 12 a vialink 50 a. If the total value of capacitance (C1+C2) is large (typicallyaround 50 micro-farads), the low shunt impedance Z_(T) may have asignificant effect on the result of a flash test performed by tester 17on panels 10.

Reference now made to FIG. 12 b which shows further details ofcompensation unit 17 a according to a feature of the present invention.Compensation unit 17 a has a programmable current injector 130, circuitanalyzer 128 and processor 126.

Programmable current injector 130 has a voltage source E 1 which may beconnected to an electronic module 12/12 a using terminals A. A firstpositive terminal of voltage source E1 and a first negative terminal ofvoltage source E 1 provides terminals A. The first positive terminal ofvoltage source E 1 is connected to node P. A second positive terminaland a second negative terminal of voltage source E1 is connected acrossa series connection of capacitor C_(p) and resistance R_(p) at node Mand ground. One end of capacitor C_(p) connects to node M and the otherend of capacitor C_(p) connects to one end of resistor R_(p) at node N.The other end of resistor R_(p) connects to ground. A first positiveterminal of current source G₂ connects to node P and a first negativeterminal of current source G2 connects to ground. Terminals B areprovided from connecting to node P and ground. A second positiveterminal of current source G₂ connects to node N and a second negativeterminal of current source G₂ connects to ground.

The input to circuit analyzer 128 is derived from node P. The output ofcircuit analyzer 128 goes into the input of processor 126. Processor 126has two outputs (shown by dotted lines) which program/control currentsource G2 and voltage source E1. Circuit analyzer 128 measures a circuitparameter of electronic module 12/12 a. The circuit parameter measuredby circuit analyzer 128 is preferably the shunt impedance of electronicmodule 12/12 a. Processor 126 is preferably configured toprogram/control current injector 130 using the circuit parametermeasured by circuit analyzer 128.

Reference is now made to FIG. 12 c and to FIG. 12 d according to afeature of the present invention. FIG. 12 c shows a simulation circuit121 a which has a pulse generator 120 with an output voltage and current124 connected to a test circuit 122 a. Simulation circuit 121 is anequivalent circuit representation of a flash testing system. Pulsegenerator 120 is the equivalent circuit representation of a flash lamp16 used to irradiate a photovoltaic panel 10 and test circuit 122 abeing the equivalent circuit representation of a photovoltaic panel 10.Pulse generator 120 has a voltage V1 which is a pulse of typically 33volts peak, rise and fall time of 0.01 milliseconds and pulse durationof 0.54 milliseconds. The pulse from voltage V 1 is applied to testcircuit 122 a via resistor R_(g) which is connected in series betweenvoltage V 1 and test circuit 122 a. Test circuit 122 a has a resistanceRpm which is connected in series between the output of pulse generator120 and ground. FIG. 12 d shows the simulation results of test circuit122 a as output voltage and current 124 as a result of pulse V 1 beingapplied to test circuit 122 a. Output voltage and current 124 has a peakvoltage of 27V and current of 5.4 A which are in phase.

Reference is now made to FIG. 12 e and to FIG. 12 f according to afeature of the present invention. FIG. 12 e shows a simulation circuit121 b which has a pulse generator 120 with an output voltage and current124 connected to a test circuit 122 b. Simulation circuit 121 b has thesame elements as shown in FIG. 12 b but with the addition of a capacitorC_(m) connected in parallel with resistor R_(pm) in test circuit 122 b.Capacitor C_(m) in test circuit 122 b represents the total shuntcapacitance for example of module 12 a connected to panel 10. FIG. 12 fshows the simulation results of test circuit 122 a as output voltage andcurrent 124 of test circuit 122 b as a result of pulse V1 (33 voltspeak, rise and fall time of 0.01 milliseconds and pulse duration of 0.54milliseconds) being applied to test circuit 122 b. Output voltage andcurrent 124 are now not in phase with voltage (27V) lagging and currentpeaks which reach 40 A.

Reference is now made to FIG. 12 g , FIG. 12 h and FIG. 12 i accordingto a feature of the present invention. FIG. 12 g shows a simulationcircuit 121 c which has a pulse generator 120 with an output voltage andcurrent 124 connected to a test circuit 122 b. Simulation circuit 121 chas the same elements as shown in FIG. 12 e but with the addition ofcompensation unit 17 a connected in parallel with capacitor C_(m) intest circuit 122 b. Capacitance C_(m) represents the total shuntcapacitance for example of module 12 a connected to panel 10 with bypass50 a activated as an un-blown fuse link (step 1201). In compensationunit 17 a, circuit analyzer 128 measures a circuit parameter of testmodule 122 b. The circuit parameter measured by circuit analyzer 128 ispreferably the shunt impedance of test module 122 b or the shuntcapacitance of test module 122 b. Processor 126 is preferably configuredto program/control current injector 130 using the circuit parametermeasured by circuit analyzer 128. Compensation unit 17 a can inject acurrent into test module 122 b in order to compensate for the shuntcapacitance of test module 122 b (step 1203) when performing a flashtest. FIG. 12 h shows the compensated output voltage and current 124 oftest circuit 122 b as a result of pulse V1 (33 volts peak, rise and falltime of 0.01 milliseconds and pulse duration of 0.54 milliseconds) beingapplied to test circuit 122 b. Output voltage and current 124 are now inphase and output voltage and current 124 represents the current/voltagecharacteristics of resistance Rpm in test circuit 122 b.

Reference is now made again to FIGS. 12 a, 12 b and to FIG. 12 j whichshows a method 1220, according to an embodiment of the presentinvention. With link 50 a activated as an un-blown fuse link (step 1201)a low impedance path exists between the input and the output of module12 a. Prior to a flash test of panel 10 using tester 17, located incompensation unit 17 a, is circuit analyzer 128 which measures (step1223) a circuit parameter of the output of electronic module 12 a withthe input of module 12 a connected to pane 110. The circuit parametermeasured by circuit analyzer 128 with fuse link 50 a connected accordingto step 1221 may be the impedance of capacitors C1 and C2 in parallelwith panel 10 and with flash tester 17 disconnected. Alternatively, thevalue of shunt impedance for module 12 a may be measured (to provide anoted value) prior to attachment to panel 10. Processor 126 ispreferably configured to program (step 1225) and/or control currentinjector 130 using the circuit parameter measured by circuit analyzer128 or from the noted value. With flash tester 17 operatively attachedto compensation unit 17 a, module 12 a and panel 10, a flash test isperformed where the current injection by compensation unit 17 asimultaneously triggers (step 1227) a flash test of a panel using tester17.

The definite articles “a”, “an” is used herein, such as “a converter”,“a switch” have the meaning of “one or more” that is “one or moreconverters” or “one or more switches”.

Although selected embodiments of the present invention have been shownand described, it is to be understood the present invention is notlimited to the described embodiments. Instead, it is to be appreciatedthat changes may be made to these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined bythe claims and the equivalents thereof.

The invention claimed is:
 1. A system comprising: a photovoltaic (PV)panel comprising a PV positive output terminal and a PV negative outputterminal; a circuit comprising a positive input terminal, a negativeinput terminal, a positive output terminal, and a negative outputterminal, wherein the PV positive output terminal and the PV negativeoutput terminal are respectively connected to the positive inputterminal of the circuit and the negative input terminal of the circuit;and a switch directly connected between the positive input terminal ofthe circuit and the positive output terminal of the circuit, andwherein, when the switch is in a closed state, the switch provides a lowimpedance path between the PV positive output terminal and the positiveoutput terminal of the circuit.
 2. The system of claim 1, wherein theswitch is a solid state switch.
 3. The system of claim 1, wherein thecircuit is configured to receive power from the positive PV outputterminal and the negative PV output terminal.
 4. The system of claim 1,wherein the negative input terminal and the negative output terminal aredirectly connected.
 5. The system of claim 1, wherein the negative inputterminal and the negative output terminal are connected using a male MC4connector and a female MC4 connector.
 6. The system of claim 1, whereinthe switch is opened and closed by applying an electromagnetic signal toa gate of the switch using a controller and a gate driver.
 7. The systemof claim 1, wherein the switch is opened and closed in response to acommunication signal, and wherein the circuit comprises a communicationmodule configured to receive the communication signal, and wherein thecircuit is configured to open and close the switch by applying a pulseto a gate of the switch using a controller and a gate driver.
 8. Anapparatus comprising: a circuit comprising a positive input terminal, anegative input terminal, a positive output terminal, and a negativeoutput terminal, wherein the circuit is configured to convert power fromthe positive input terminal and the negative input terminal to thepositive output terminal and the negative output terminal; and a switchdirectly coupled between the positive input terminal of the circuit andthe positive output terminal of the circuit, wherein when the switch isclosed, the switch provides a low impedance path between the positiveinput terminal and the positive output terminal.
 9. The apparatus ofclaim 8, wherein the negative input terminal and the negative outputterminal are directly connected.
 10. The apparatus of claim 8, whereinthe circuit is connected to a photovoltaic panel.
 11. The apparatus ofclaim 8, wherein the switch is a solid state switch.
 12. The apparatusof claim 8, wherein the negative input terminal and the negative outputterminal are connected using a male MC4 connector and a female MC4connector.
 13. The apparatus of claim 8, wherein the switch is openedand closed by applying a signal to a gate of the switch using acontroller and a gate driver.
 14. The apparatus of claim 8, wherein theswitch is opened and closed in response to a communication signal,wherein the circuit comprises a communication module configured toreceive the communication signal, and wherein the circuit is configuredto open and close the switch by applying a pulse to a gate of the switchusing a controller and a gate driver.
 15. A method comprising:harvesting power from a photovoltaic panel; converting the harvestedpower from a positive input terminal of a circuit and a negative inputterminal of the circuit to a positive output terminal of the circuit anda negative output terminal of the circuit; and bypassing the circuit byclosing a switch, wherein the switch is directly coupled between thepositive input terminal of the circuit and the positive output terminalof the circuit, and wherein closing the switch provides a low impedancepath between the positive input terminal of the circuit and the positiveoutput terminal of the circuit.
 16. The method of claim 15, wherein thenegative input terminal and the negative output terminal are directlyconnected.
 17. The method of claim 15, wherein the negative inputterminal and the negative output terminal are connected using a male MC4connector and a female MC4 connector.
 18. The method according to claim15, wherein the closing of the switch comprises communicating with thecircuit.
 19. The method of claim 17, wherein the switch is a solid stateswitch.
 20. The method of claim 15, wherein the switch is opened andclosed responsive to receiving a communication signal, and wherein thecircuit comprises a communication module configured to receive thecommunication signal, and wherein the circuit is configured to open andclose the switch by applying a pulse to a gate of the switch using acontroller and a gate driver.